1. Field of the Invention
The present invention relates to aircraft with electrical fly-by-wire controls and, more particularly, to the architecture of the flight control system for such aircraft.
2. Discussion of the Background
It is known that an aircraft with electrical fly-by-wire controls has controls, such as sticks, ministicks, rudder bars, etc., equipped with electrical transducers so that they generate electrical control instructions which represent the action that a pilot exerts on them. It also includes a computer of flight control commands which, on the basis of the electrical control instructions generated by the controls and of control parameters originating, for example, from sensors, produces electrical operating commands that the flight control computer applies to actuators tasked with moving the control surfaces of the aircraft.
It is also commonplace for such an aircraft to have an automatic pilot capable, under certain circumstances, of piloting the aircraft in place of the pilot. As is also known, an automatic pilot consists essentially of a navigation computer and of a control computer. The navigation computer receives guidance instructions (indicated to it by the pilot) and guidance parameters (sent to it by sensors or by an inertial unit, for example), and from these guidance instructions and parameters produces automatic pilot instructions. For its part, the control computer converts these automatic pilot instructions into commands for operating the automatic pilot, which it applies to the actuators of the control surfaces of the aircraft.
Depending on the known embodiments of automatic pilots, the commands for operating the automatic pilot are applied to the actuators either directly or via the flight control computer. In the latter case, it will be noted that the flight control computer receives, from the automatic pilot, the commands for operating the automatic pilot which have already been fully produced and that in consequence its role amounts simply to transmitting the automatic pilot control commands unmodified.
Whichever of these two embodiments is on board the aircraft, it must also, however, be pointed out that, in such a known architecture, it is necessary to provide two control functions, namely one for the flight control computer and the other for the automatic pilot. Aside from the fact that this gives rise to significant costs, it may happen, owing to constraints of the system, that the control functions differ, particularly as regards the calculation power, the acquisition of parameters, the monitoring, etc. It is therefore compulsory to develop and to validate two control functions. In addition, a structure such as this does not make it possible to minimize the delays between the inertial information and the operating commands given by the automatic pilot to the control surfaces.